Category: Microsoft Defender for Office
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Blocking onmicrosoft.com Emails in Exchange Online Protection
There is a considerable uptick in emails from the default domain in Microsoft 365 tenants. These emails come from senders @ tenant.onmicrosoft.com and are not your tenant. Microsoft recently announced recipient external sender limits to reduce this, as the default is 10,000 recipients per day, but will get an additional restriction of no more than…
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Integrating Microsoft 365 SafeLinks and Mimecast Targeted Threat Protection
If your email protection filter is provided by Mimecast, then you might also have enabled Mimecast Targeted Threat Protection (TTP). TTP, like Microsoft Defender for Office SafeLinks will rewrite the URLs in email messages, but unlike SafeLinks will not rewrite or redirect them in Office documents or Teams chat, channel and meetings. Therefore as both…
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SSL Inspection and Microsoft 365
There are a number of features in Microsoft 365 that do not work if SSL Inspection (also known as TLS Interception) is enabled on your device or network provider. You need to disable the listed URLs that Microsoft provides in its documentation. The problem is there is a lot of disconnected documentation! This blog post…
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Blocking More Obvious Phish – Attachment Filtering
One relatively easy way to block some categories of phishing email is to block the attachment type that is sent with some of these messages. For example, I have had a few of these recently: Hovering over the attachment I see the filename, and it ends .shtml. This attachment is for server-side HTML (SSI includes…